A disc drive includes a plurality of stacked discs which are rotationally supported relative to a disc spindle and an actuator assembly movably supporting a plurality of head gimbal assemblies for reading and writing data to the discs. The actuator assembly includes an actuator drive typically a voice coil motor for actuating the head gimbal assemblies relative to selected data tracks of the discs.
The voice coil motor includes a stator defining a permanent magnetic field and a rotor coupled to an actuator block supporting the head gimbal assemblies. The rotor includes a bobbin having a voice coil wound about the bobbin. A voltage is supplied to the coil to selectively operate and move the actuator block to align the head gimbal assemblies relative to predetermined data tracks of the discs.
A typical stator includes upper and lower pole plates or backirons which are supported relative to the disc drive assembly in a spaced relation and include a magnet coupled thereto to define a flux gap therebetween. The rotor (bobbin and voice coil) coupled to the actuator block moves in the flux gap between the upper and lower pole plates.
Increased capacity disc drives are consistently being developed which have different operating requirements. For example, high density drives have developed which require higher capacity motors for moving the actuator block. Thus, it was desirable to develop a higher capacity actuator drive for providing more power for operating the actuator block of an increased capacity disk. Higher energy magnets to operate an actuator block of an increased capacity disc drive of the type described are difficult to energize, handle and assembly with known apparatus and techniques.